Automobiles can mean various things to their owners. To many, an automobile is nothing more than transportation but, things such as inferred status, appearance, economy, comfort and ergonomics may be all important. To some, anything automotive may be a passion, and these people are classified as collectors, customizers, maybe drivers or perhaps, just “car crazy”. Many true enthusiasts prefer a manual transmission above an automatic for reasons of performance and/or precise control.
Gear ratio selection in manual transmissions is aided by a gate mechanism for guiding the shift lever movements to select a particular gear ratio. In earlier times, when engines ran at lower speeds and had relatively flat torque curves, shifting gears was not a skill issue. Engine design has since become more sophisticated, with more power at higher rpm and diminishing torque at the top end. This requires a graduated selection of gear ratios to access the performance potential. Where three-speed transmissions were once the norm, we now commonly see five and six speeds.
Having more speed ratio options does require more of the driver in skill and discernment, so assistance for speed selection in five and six speed transmissions is typically provided by “spring centering”. The industry-wide standard solution is a Belleville spring washer around the shift lever. This conically shaped spring washer is compressed as the shift lever is moved to either side of center, and the spring force urges the lever back toward center, where it aligns with the gated third and fourth speed slots.
In the standardized arrangement, centering force is equal and fixed, whether shifting from second speed to third, or from fifth speed to fourth. This is acceptable to most people, but many drivers are troubled by limitations inherent to this centering arrangement. On acceleration, heavy bias toward center is helpful for quickly shifting from second to third, but will also resist the up-shift from fourth-to-fifth. Too little bias will not give the positive centering needed for a quick shift from second to third, possibly causing a missed shift. When decelerating, down-shifts are generally made while braking and are not so time critical. Therefore, a much lighter bias toward center from fifth/sixth should be preferred, but what feels right to one driver may not be agreeable to the next. The commercially acceptable Belleville spring centering solution of the prior art addresses the gate sensing needs of every day drivers.
Competitive drivers, looking for track or drag strip performance, where every fraction of a second counts, want each shift to be quick and certain, with never a miss. Particularly in “drag” racing, the driver will minimize time lost during a shift by simply “fanning” the clutch pedal as the shift lever is slammed from second to third or fourth to fifth. Such shifting requires the driver to have perfect timing and confidence that he will hit the gate opening. The shift from second to third is particularly critical, so a heavy spring centering force is desirable here; heavy enough to push the shifter across to the third speed gate slot as it passes through neutral. Because the industry standard arrangement dictates equal force on the opposite gate that same heavy force will prevent an accurate and timely up shift to fifth.
Modified engines in competition are significantly more powerful than stock, even exceeding stock transmission capacity. Thus, serious competitors frequently replace their stock transmission with a more suitable unit for performance and/or reliability. Installing a non-stock transmission usually creates a host of problems, such as frame or sheet metal interferences, mounting adaptation, driveshaft changes and shift lever location. For the most part, these problems yield to skilled mechanics using available parts. Gearshift lever relocation is generally resolved by bolting a forged or welded offset lever to the transmission stub shaft. The stub shaft bolts are close together, so that the severe, reversing shear loads make loosening just a matter of time. The aforesaid spring-centering issue is shrugged off for lack of a solution.
Objects of the present invention are, first, to provide speed selection apparatus, which facilitates ergonomic adaption of a non-stock transmission into an automobile. A second object is to provide an adjustable spring centering bias, according to an individual driver's desire. A third object is that this spring centering bias be separately adjustable from left to center and from right to center. A fourth object is to provide apparatus, which permits adjustment of the gear-shift lever location according to the individual driver's preference. Yet other objects are that the apparatus of the present invention be inexpensive, rugged and capable of being quickly and easily adjusted, according to the driver's preference.